Polymeric materials



Patented Oct.t2 7, a o

j roLmmc Marnmats;

.David M. mama; wu mmn, DeL, aam, to

E. Ldulont de Nemourspa Company. Wilinvention relates to polymeric materials linear polyamides. i i

This invention has as anobject a process for l 3 modifying theproperties o1 syntheticlinear-polyamides. LA further object is'a process ior decreasing the solubility of water soluble poly-v amides. "A further object is to raise the melting point ofthese polyamides. A iurther object is i the production of new and usefulcornpositions oi of filaments, ribbon, illmsflandfthe like. j Other objects will appear hereinafter, E

These objects are accomplished by a process which comprises treating a water-soluble synthetic linear polyamide with an insolubilizing agent comprising anionizable salt containing a metal having avalencegreater 'than 2 orcapable.

Thetreatof being oxidized to such valence. ment is preferably applied to the polyamide in the form oi films, flbers, bristles and the like,

after which the article is baked below the moting point of the polyamide, orinthe case of photo-sensitive salts, the article is exposed to ultravioletlight. j The synthetic above areoi the general type described in Patents 2,071,250, 10711253, and 2,130,948.

polyamidesxwith which this invention is consoluble. Bywater-soluble polyarnides is meant those polyamides which :are soluble either in 7 water alone or in aqueousalcohol solutions. The term polyamide refers not onlytothepolyamides obtained from polyamide-forming reactants alone (including the interpolyamidesi obtained from mixtures of these reactants) butlalso.

to linear polymers containing a plurality of amide groups as an integral part of the main chain of atoms, asfior instance, the ester-amide interpolymers. i

Water-soluble, polyamides: particularly well adapted to the practice. of this invention are Ioundinthe class oifpolyamides which contain hetero atoms of the oxygen family and which are described in Patents: 2,158,064 and 2.191556.

, These polyamides, some 01 which are very soluble in watengrepresenta large class. For example, it is possible tomake polyamides in which the diamine represented contains the hetero mlng-ton, Del., corporatlon'ol Delaware and more particularly to treatment of synthetic linear polyamides referred to The 1 cerned are those of this type which are water Application, septemterzr, 1939, i sermmzea ae, y

(or. 18-48) i o the diamine ordibasic-acld reactant is of the hetero atom type. A mixture 01 diamines and] or dibasic acids can also be used in preparing interpdlyamides.

also be used in conjunction with the diamines and dibasic acida o v Another useful type oi water-soluble polyamide is prepared by the interpolymerization '10" 0t hexamethylene diammonium adipate with: matter; Still another object is the preparation "epsilon-aminocaproicacid, or their equivalents,

andlirom this solutioncan be readily cast into treatment of this invention. U i

In carrying outthe invention with polyamide:

15 iilmswhich are further given the insolubilizing soluble in water alone, theusual practice is to castthe film from solution, drying the film under 20 ordinary conditions of temperature and humidity,

coating or impregnating the film with a saturated aqueous'solution of the insolubilizing agent, and then baking the film. gOneor more coats may .be applied with a brush or spray after which the film is baked from 8 to 16 hour-sat about l00-120 C. In the case of solutions of the polyamide in aqueousalcohol or miscible ,solutions or water with other organic solvents, 1 the insolubilizing agent is addedas such, or in -solution in the same solvent, to the polyamide solution just prior to casting the film, or the agent is added to the film aftercasting but before it hasdried. The film may also be clipped momentarily in the solution or the insolubilizing agent, 5 or in the agent itseli,,provided the agent is capable of swelling and penetrating the film. Generally the insolubilizing agent is applied in excess. The application softens and swells the film, and may even partially dissolve "it: This permits adequate penetration and allows insolubilization to be effected in the subsequent heating .or radiation step.

Polyamides referred to hereinafter are preparedby heatinga salt of a dibasic acid and a diamine oz by other methods described inPatent 2,130,948, or by. polymerizing arr amino-acid or i an amide forming derivative thereof, as described in Patent 2,071,253. Interpolyamides are prepared by using more than one polyamide-forming composition,e. g., a mixture of diamine-dibasic' acid salts. ..The,polyamides prepared fromthe' polymer-fuming compositions listed below, and

reierredi to by the letters A to I, were used in the followingexamples illustrating the practice of. thisinvention.

7 Other bifunctional reactants, such 5 as amino acids, hydroxy acids, and glycols, can

COMPOSITION 85% triglycoldiamine-adipic acid-% hexamethylenediamine-adipic.acid.

. 70% triglycoldiamine-adipic acid-30% hexamethylenediamine diglycolic acid.

polyvinyl alcohol).

' The percentage compositions refer to the parts by weight of the salt in the polymer-forming compositions in the reactive mixture before polymerization was eflected. The polyamides (including interpolyamides) and their copolymers were made into 10% aqueous solutions by weight.

EXAMPLEI Filmscast-from aqueous solutions of compositions A, B, and C are insolubilized by treatment with aluminum sulfate and with aluminum ace- 90% triglycoldiamine-adipic acid-10% decatats. In applying these reagents, an excess of a saturated aqueous solution of the salt is coated on the films. The treated films are then baked overnight at 100 C. After the films have cooled to'room temperature,.they are immersed in water at 25 C. Table I gives the length or time for complete solution of untreatedfilms, and the length of time for partial'solution or crumbling for the treated films. It is apparent that the treatment has a marked insolubilizing action.

Tam I Insolubilization of films Insolnbilizing agent .4. a c

tit idea It! Al (804)s 25 m Al(O0CH;)| 46 Control (nntreatedfilm a 10 A 10% aqueous solution of composition B is mixed with an equal volume of aqueous 5% ammonium dichromate and is cast into films on two glassplatess Thefilmsare allowedto dryinthe dark. After they are dry, one-half of each film is covered with tinfoil and the films are exposed to ultraviolet light. After such exposure, the films are immersed in water at 25 for '12 hours. The unexposed portions of the films dissolve rapidly whereas the exposed parts are not dissolved at the end of 72 hours.

EXAIDPLEHI Interpolyamides of compositions A, D, and E, are cast into films and a saturated aqueous solution of ammonium dichromate is applied to each by means of a paintbrush. The films are then baked at 150-160 C. for 16 hours in an atmosphere of nitrogen. The treated films do not dissolve when immersed in boiling water for 5 minutes, whereas the control film (untreated) dissolves almost immediately in water at 90 C.

EXAMPLE IV Interpolyamide composition E is dissolved in water and cast into films on glass plates. Two parts by weight of interpolyamide is used in preparing each film. 'Two parts by weight of a metal salt, indicated below, dissolved in 15 parts of water is added to each plate. before the films are completely dry. The films are then permitted to dry at room temperature and are finally baked at C. for 16 hours. The following salts are used: borax, manganese chloride, cobalt chloride, lead diacetate, nickel sulfate, ferric chloride, zirconium sulfate, and bismuth trichloride. The salts in a valence state of 2 but capable of being oxidized to a higher valency show some ability to effect insolubilization, but those having a valency of 3 or more showed marked aptitude in effecting insolubilization. For example, films treated with ferric chloride and bismuth trichloride did not dissolve even after immersion in water at 25 C. for a period of 24 hours. All the other EXAMPLEV Composition H dissolved in 50% aqueous ethanol, so as to obtain a 20% solution by weight, is mixed with a 10% alcoholic solution of ferric chloride, and films are cast from this homogeneone solution. The films are baked for 8 hours at a temperature of C. The films are then immersed in 50% aqueous ethanol at a temperature of 65 C. The control film dissolves in 30-40 minutes, whereas the treated film shows no signs of solution at the end of 4 hours in thisethanol bath. The melting point of the treated film is -190 C., whereas the untreated film melted at l'l5-180' C.

EXAMPLEVI Composition G is made into a 10% aqueous solution and is cast into films. These are treated with aqueous solutions of ferric chloride and ammonium dichromate. A 10% solution 0! composition I is also cast into a film and coated with an excess of ammonium dichromate. The films are baked for 8 hours at 120 C. All the films show marked insolubility and elevation ill-Q1! a melting point, as illustrated in Table II.

' Tasu: II

Increase of melting point of films To 120 parts of a 10% aqueous solution of interpolyamide composition D is added ".5 parts of a 14% aqueous solution of ammonium dichromate. The aqueous mixture is fiowed on photolithographic zinc plates in a dark room and allowed to dry. When dry, the plates are covered with a piece of heavy paper in which letters have been cut. The plates are then exposed to ultraviolet light for two minutes. The exposed portions of the polymer coated plates, 1. e., the portion exposed by the letters in the paper, become essentially insoluble whereas the scribed for'the first plate. In another modification theparti'ally exposed portions remain solublef One plate is then washedto remove the soluble portions of the c polymer film leaving the insoluble portions triglycol beta-methyl adipamide.

(lettersr intact. Whilestiliwet, 'this-lplate is it gently with a varnish ink prepared by grindingilead chromatein linseed oilwf The ink j adheres only to the photo-insolubilized' "letters that remain after the working step." {The initials 'werethen printed on paperby squeegeeing a pieceof paper on the plate. Another plate after. exposure tdultraviolet light (through -the initial "stencili is coated completely with athinfllm of the varnish ink before washing andis then im'-- mersed in water." The polymer and ink are thereby removed excepton the photohardened section. Thlsplate could then be used in printing as de=- plates aretreated with dilute nitric acid. This treatment causes the unexposed portion of the plate to be etched, whereas the exposed portion is polytriglycol suberamide, and polytriglycol aselamide, polytriglycol diglycolicamide, and poly amides derived byicoloint polymerization of the -polvamide forming compositions which yield the foregoing water-solublepoLvamides and such polyamide-forming compositions as hexamethyl- *ene diammonium adipate, hexamethylene diam.-

monium sebacate, "decarnethy'lene diammonium 10" R anoic acid, maybe 1 i i v This invention isparticularly valuable in conadipate, fi-aminocaproic acid, llalninoundecnctionrwith the and impregnation, arts,

The present process makes possible the deposition ofifllmsor protective coatings of the polyamide, whichmay besubsequently insolubilized, on wire and on fabrics such as cloth. paper, leather. etc.

A noteworthy feature of this invention is the fact protected by the insolubilizedpolyamide which 4 acts as a resist material. This procedure is useful in various photomechanical printing processes such as photoengraving and photolithog'raphy. The plates may be made of other metals than zinc, e. g., aluminum andcopper.

The present process may be advantageously carried out with mixtures of the polyamides and other types of polymers compatible therewith- 3o 7 and with the aqueous solvent. Thesemodifled compositions, in addition to the polyamide, may

comprise foriinstance products such as polyvinyl I alcohol, polyvinyl alcohol-boric. acid complex, partially acetalized polyvinyl alcohol, partially hydrolyzed polyvinyl acetate, polymethacryl amide, and water soluble jinterpolymers of styrene with other vinyl compounds. I

d The lonizable metal salts used of this invention aresalts containing metals falling within groups III to VIII of the periodic table. The most effective {of these agents are salts containing metals in groups VtoVIII.

i Reaction of the, ionizable salts *with'thepolyamides occurs at comparatively low temperatures but a temperature of' atleast .75 to-80"C.is desirable to make the reaction feasible from a time in the practice standpoint. long as the reaction is carried out under non-oxidizing conditions, e. g.,in an atmosphere of nitrogen, temperatures iustshort of the decomposition temperature or melting point of the polyamide composition may bejused. ,Tem-

- peratures ranging from 1o0lto1 I20 C. are especially suitable,tfor insolubilizationcan be effected without the necessity of protecting the films with nitrogen to prevent discoloration. The films are generally insolubilized within ,8 hours baking.

. Considerable alterationin solubility can be obtained inonly l or 2 hours, but baking for 8 to 16 hours is somewhat more effective and pro longed baking does not have any deleterious effect on the final product. When ultraviolet light is used to effect insolubilization, e. g., in connection The polyamides are preferably treated while in pellicular" form with the insolubilizing ionized metal salts. The treatment may, however, be applied to other polyamide articles such as ribbons, bristles,;flbers, fabrics, and massive molded forms. v

Examples of other polyamides suited to the practice of this invention include such watersoluble polyamides as polytriglycol sebacamide, 75

v with alkaline dichromates as described in Ex amples II and VII, only a short exposure'isnecesany. i v

fold stencil sheetingcoatings. I

Asmany apparently widely different embodi-- in the appended claims.

that the melting point of the polyamide or poly-- amide composition used is markedly raised. The present process is also useful in the preparation of insoluble films for use in photography, photomechanical reproductions, and lithography. More specific examples of such ,uses are offset printing,

silk-screen printing; duplicating pads, and mam-- ments of this invention may be made without departing from the spirit and scope thereof, it is to be understood thatI do not limltmyself to the specific embodiments thereof except as defined I claim:

. 1. In a process fordecreasing the solubility of p a water soluble synthetic linear polyamide article presenting a large surface area, the step consisting of treating said article with an ionizable salt of a metal falling within groups III to VIII of the periodic table. p r

as process which comprises heating a composition comprising a water-soluble synthetic linear polyamidearticle presenting a large surface area and anionizable salt of a metal falling 7 within groups III to VIII of the periodic table.

, izable salt of a metal falling within groups In to VIII of the periodic-table,

3. A process which comprises exposing to radiant energy an article comprising a watersoluble synthetic linear polyamide and an ion-- 1!. A process which comprises exposing to ultravioletlight an article comprising a water -soluble synthetic linear polyamide' and a photosensitive ionizable salt of a metal falli'ng within groups III to VIIIof the periodic table. I a

5. The process set forth in claim 2 which i said composition is treated in pellicular form with said salt.

6. The process set forth in claim 3 in which said composition is treated in pellicular form with said salt.

- '7. The process set forth in claim '4 in which saidsalt is an alkaline dichromate.

i 8. The process set forth inclaim 4 in which said salt is ammonium dichromate.

9. A process which comprises exposing to radiant energy selected areas of an article comprising .a water-soluble synthetic linear polyamide and an ionizable salt of a metal falling within groups III to VIII of the periodic table.

10. A process which comprises adding to a solution of Water-soluble synthetic linear polyamide anionizablesalt of a metal falling within groups III to VIII of the periodic table, forming said solution into an article comprising said polyamide and salt, and baking said article.

11. A continuous self-supporting film comprisin: a water-soluble synthetic linear polyamide and an insolubilizing agent comprising an ionizable salt of a metal falling within groups In to VIII oi the periodic table. I

12. A film sensitive to radiant energy comprising a photo-sensitive salt and a synthetic linear polyamide, said polyamide constituting the sole film-forming material in said film.

13. A film sensitive to radiantenergy which 10 comprises an intimate mixture of a photo-sensitive salt and a synthetic linear polyamide.

14. A process for making polyamide articles which comprises extruding a solution of watersoluble synthetic linear polyamide in the form 0! the desired article and then heating the article with an ionizable salt of a metal falling within groups III to VIII of the periodic tableuntil the article is substantially insolubleln water.

DAVID M. McQUEEN. 

